• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.554-558
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• 2004

With the improvement of living quality, people's desire for quiet living environment keeps increasing. In particular, complaints about the noise emission by constrcution equipments around residential areas take most part of the noise related complaints. In this study, noise marking obligation system for the high noise construction equipment have been proposed to reduce the noise level and protect the well-being of citizens. For this purpose, construction equipment used in the country were surveyed and compared with that of the European Directive/2000/14/EC. As results, 20 kinds of construction equipment were proposed for the obligated noise marking, while 13 kinds of construction equipment were proposed for the equipment subject to permissible noise level, thus the obligated noise marking and certification.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.72-73
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• 2010

In this paper, the main noise sources and its radiated noise levels of upwind horizontal-axis wind turbines are experimentally and theoretically investigated. Theoretical predictions for indentifying the dominant source locations are made by using the empirical noise prediction model of Brooks et al. (1989) for the airfoil self noise. Through the comparison of theoretical results with the experimental results, turbulence-boundary-layer-trailing-edge (TBL-TE) noise is revealed to be the dominant source over all frequency range and separation and stall (S-S) noise is possibly important in the relative lower frequency range compared with TBL-TE noise.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1900-1907
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• 2010

In this paper, a recurrent cerebellar modulation articulation control with praticle swarm optimization (PSO) method has been investigated for improvement of noise attenuation performance in active noise control system. For narrow band noise, FXLMS and RCMAC has a partial satisfactory noise attenuation. However, noise attenuation performance is poor for broad band noise and nonlinear path since it has linear filter structure. To improve this problem, a RCMAC with PSO is proposed and it is shown that satisfactory noise attenuation performance is obtained by some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.75-82
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• 2007

This paper presents practical work on the reduction of gear whine noise. In order to identify the source of the gear whine noise, transfer paths are searched and analyzed by operational deflection shape analysis and experimental modal analysis. It was found that gear whine noise has an air-borne noise path instead of structure-borne noise path. The main sources of air-borne noise were the two global modes caused by the resonance of an axle system. These modes created a vibro-acoustic noise problem. Vibro-acoustic noise can be reduced by controlling the vibration of the noise source. The vibration of noise source is controlled by the modification of structure to avoid the resonance or to reduce the excitation force. In the study, the excitation force of the axle system is attenuated by changing the tooth profile of the hypoid gear. The modification of the tooth profile yields a reduction of transmission error, which is correlated to the gear whine noise. Finally, whine noise is reduced by 10 dBA.

• Journal of Environmental Impact Assessment
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• v.19 no.6
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• pp.553-561
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• 2010

Railway noise barrier is generally used with welding of joint rail for railway noise reduction in our country. In this study, method for performance evaluation of railway noise barrier using insertion loss was suggested in case of without having noise measurement results before barrier installation. For this, railway noise measurements were performed in commercial high-speed railway site which has railway noise barrier. As a noise level before noise barrier installation, predicted noise level were used. From this method the performance evaluation for railway noise barrier were performed accurately and efficiently.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1139-1144
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• 2007

The use of noise barrier is being increased to reduce the environmental noise in these days. Also, many noise reducers installed at the top of noise barrier are developed for improving the efficiency of noise reduction. So we evaluate the performance of the noise reducers and compare the results among the others. Results of field tests show that the insertion loss due to the noise reducers is up to 10.6 dB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.163-168
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• 2011

Noise map is drawn up under launch environment through analyzing jet noise of guided weapon in this research. This has an important significance in terms of having an opportunity to look at influence of noise which is caused by guided weapon in the surrounding environment. In this paper, the magnitude of jet noise that was measured by using microphone and the result of numerical analysis that was gained by using ENPro which is environment noise prediction program are shown. At this point estimation of noise source was based on ISO 9613. Finally noise map derived from results mentioned above will become useful material when setting safety guide for protecting hearing loss of operator of weapon system in the future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.558-567
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• 2011

One of the main objectives of noise control act is to define and ensure application and respect of noise exposure limits. Most advanced countries have prepared a legal framework for noise limits either by national laws, ordinances or municipal by-laws. A large number of advaced countries have adopted the $L_{eq}$ index for the main sources of noise (road, railway, industry). The exception is aircraft noise for which regulatory practice is highly disparate. These differences in the indices adopted, the periods and areas to which regulations apply, definitions of measurement conditions and ways in which noise levels are calculated make it difficult to compare the current advanced countries standards. This study presents the current noise abatement policy of the advanced countries and proposes the improvement of the current noise abatement policy of Korea to catch up with it of the advanced countries.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.533-536
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• 2003

The Low frequency(1-200 Hz) noise levels radiated by road traffic were investigated. The results showed that the peak pass-by noise of truck with speed of 60km/h was about 75㏈. For the infra-sound frequency range, the noise was about 65㏈ and it was less value than expected. But the noise level will be increase as increasing the speed. The pass-by noise for train was also measured for comparison. The peak train noise was about 95㏈ and it will be enough noise level for a human body to give nuisance.

• Journal of KSNVE
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• v.7 no.5
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• pp.757-764
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• 1997

The well-developed noise separatrion techniques are applied to the V8 RG8 Diesel engine for the engine noise reduction of a commercial vehicle. For various loads and engine RPM's, the contribution of the combustion oriented noise and the mechanically induced noise was calculated under the small variations of the injection timing. For the given Diesel engine the mechanical noise is dominant for low rpm, and the contribution of the combustion noise becomes greater as the rpm increases. The combustion noise is dominant around 2kHz range or under 50% loading condition.